Aeroplane-propeller



E.T.GOVB

AEROPLANE PROPELLER.

APPLICATION man DEC- 9. I919.

1,380,057. Patented May 31, 1921.

2 SHEETS-SHEET I.

E. T. eovs.

AERGPLANE PROPELLER.

APPLICATION FILED DEC- 9. I919.

Patented May 31, 1921.

2 SHEETSSHEET 2.

. w I m I l I t uurreo stares EMERY 'I'. GOVE, OF BERKELEY, CALIFORNIA.

AEROPLANE-PBOIPELLER.

Specification of Letters Patent,

Patented May 31, 1921.

Application filed December 9, 1919. Serial No. 343,563.

To all whom it may concern Be it known that I, EMERY T. Govn, of Berkeley, in the county of Alameda and State of California, have invented certain new and useful Improvements in Aeroplane- Propellers; and I do hereby declare the following to be a full, clear, and exact descrlption of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention has reference to the design of propeller blades which are capable of being axially shifted without interfering with their rotation, the object being to change the effective surfaces of the blades so that they will partially retard the speed of the machine or completely retard 1t and operate as brakes to facilitate landing.

This broad idea is known in the art but the forms in which attempts have been made to embody it have not been successful in practice. This is mainly due to the fact that they have not been capable of res1st1ng the strain to which the blades of high power motors are subjected. This will be appreciated from the fact that the blades of a 100 horse power motor normally make from 1200 to 1350 revolutions per minute.

My primary objects are to provide means for so securing the blades in their hub that they can stand the strain and not be weakened by the mechanism providing for their axial shift, and to so design this securing means that a blade may readily be removed, thus facilitating the substitution of a new blade for a damaged one.

In the drawings, Figure 1 is an elevation showing the prefered assembly of propeller blades embodying my invention. Fig. 2 is detail, partly in section, and Fig. 3 avertical section of the same parts. Figs. 4, 5 and 6 are details.

The propeller hub 1 is hollow and closed by a face plate 2 secured by bolts 3 permitting ready removal to gain access to the parts by which the blades are secured. The propeller shaft 4 is driven by a motor indicated at 5 and is keyed to the central shoulder 6 of the hub by a spline 7 and held by a nut 8 on its threaded extremity bearing against the shoulder.

As the blades are alike a detail description of one and its mounting and actuating means will sufiice. The blade is bored longitudinally as at 9 throughout its entire length to receive a metallic rod 10 having a foot 12 which is channeled to inclose the free end of the blade and formed with screw holes. This is to strengthen the blade. The blade is formed in two parts 13, 14, the inner part 13 havin a sleeve 15 to receive the 6X? tremity 16 o the outer part 14, the two parts having screw holes for securing them together. A rectangular block 17 in part 13 enters a correspondingly shaped recess 18 1n part 14. The part 13 is suddenly reduced t form a shoulder 19 and a post 20 threaded near its free end. The hub has a socket 21 to receive the sleeve 15. Within thls socket and bearing against shoulder 19 and the inner wall 22 of the socket are two rings 23 formed with registering raceways for ball bearings. The walls 22 and 24 form a cas1ng through which the post 20 extends and receives at its extremity a pair of locklng nuts 25. 26 designates a nut on the extremity of reinforcing rod 10 and bearing against sultable washers between itself and the outer nut 25. Interposed between the 1nner nut 25 and the.wall 24 is a second pair of bearing rings 27.

The post 20 of the blade has a gear 28 keyed to it and located within the casing formed by walls 22, '24. This gear is turned by a suitable rack bar to effect the axial shift of the blade through the medium of parts which I will now describe.

A spider 29 is keyed upon the propeller shaft 4 but is free to move longitudinally. A collar 30 is also keyed upon the shaft and held by apin 31 as against longitudinal movement. A spring 32 is coiled upon the shaft and bears against collar 30 and the hub of the spider. A loose collar 33 is movable along the shaft by a lever 34 under the control of the operator, the collar 33 bearing against the hub of the spider.

The spider arms correspond in number to that of the blades. Each arm carries at its outer end a rack bar 35 passing transversely through the hub 1 between walls 22, 24, and meshing with the gear 28 on the post 20 of the blade. At its free end the rack bar has a curved stop arm 36 to limit the travel of the rack in one direction, to the right as viewed in Fig. 3. This stop arm is curved to conform to the gear 28 so that if the rack is moved too far the arm will contact with the gear and arrest the travel of the rack. To maintain the rack in proper relation to the gear I form its reverse side with a groove 37 to receive the end of a pin 38 tapped in the hub. This forms a guide and prevents the rack from shitting.

In practice it may be assumed that with the spring 32 under no tension the spider will be maintained at such a point lengthwise of the shaft that its rack bars will hold the blades in proper position for forward pull or other normal 0 eration. When it is desired to axially shi the blades to vary the resultant force due to their rotation the operator shifts the lever 34: to move collar 33 and the spider against the tension of the spring, thus causing the rack bars 35 to move inward and partially rotate the gears 28. It will be noted that this axial turn of the blades is independent of their bodily rotation and may be accomplished without first varying the speed of travel.

I claim as my invention:'

1. In an aeroplane propeller, the combination with a propeller hub and a plurality of blades mounted therein and capable of turning axially in their supports, said blades having gears, rack-bars meshing with said gears, stop arms on said rack bars adapted to engage said gears to limit the movement of said rack bars, and means for actuating said rack bars.

memos? 2. In an aeroplane propeller, the combination with a propeller hub and a plurality of blades mounted therein and ca able of turning axially in their supports, said blades having gears, rack-bars meshing with said gears, said rack bars having channels in their reverse sides, pins tapped in said hub and having their ends received by said chanfiels, and means for reciprocating said rackars.

3. In an aeroplane propeller, the combination with a hub, of a blade mounted therein, said blade having a longitudinal bore, a rod passed through said bore and a channel plate on the end of said rod to receive the extremity of the blade.

4. In an aeroplane propeller, the combination with a hub, of a blade mounted therein, said blade comprising two parts, one of said parts having a sleeve to receive the extremity of the other part, a rectangular block within said sleeve, and a recess of corresponding formation in the other. part to receive said block.

In testimony whereof l have signed this specification.

JEMJERY 'l. GUVE, 

